1. Field of the Invention
The present invention relates to a mold resin sealing device and a molding method for sealing a semiconductor wafer with a mold resin.
2. Description of the Related Art
Various molding methods for sealing a semiconductor wafer with a mold resin have been proposed. See Japanese Patent Kokai Publication No. 2001-44222 (Patent Document 1) and Japanese Patent Kokai Publication No. 2005-64456 (Patent Document 2), for example.
In the first method disclosed in the Patent Document 1, a semiconductor wafer 102 is set on a lower surface of an upper mold die 101 and a mold resin 112 is set on an upper surface of a lower mold die 111 as illustrated in FIG. 1, and then the upper mold die 101 and the lower mold die 111 are clamped to press and spread the mold resin 112 as illustrated in FIG. 2, thereby forming a molded resin body covering a surface of the semiconductor wafer 102.
In the second method disclosed in the Patent Document 2, as illustrated in FIG. 3, a step-like part 113 which is higher as it approaches a central region is provided on the lower mold die 111 so that a distance between the upper mold die 101 and the lower mold die 111 or a distance between the upper mold die 101 and the step-like part 113 is larger as it approaches an outer circumference part of the semiconductor wafer 102. The mold resin 112 is set on the step-like part 113 and then the upper mold die 101 and the lower mold die 111 are clamped. In the second method, as illustrated in FIG. 4, the semiconductor wafer 102 is sealed with a molded resin body 112a having a stair-like shape which is higher as it approaches an outer circumference part of the molded resin body 112a. 
However, in the first method, since a distance between the upper mold die and the lower mold die becomes narrow when clamped, a flowing spied of the mold resin between the upper mold die and the lower mold die is too fast in the outer circumference part of the semiconductor wafer and so voids occur in the mold resin because of air involved at a post on the semiconductor wafer (jetting, for example) or the like.
The second method prevents, by providing the step-like part, the flowing speed of the mold resin from becoming too fast in the outer circumference part of the semiconductor wafer and so voids which occur in the mold resin are reduced. However, in the second method, a molded resin after the molding process has an uneven surface and it is difficult to employ a next process on the uneven surface of the molded resin.